In solutions for peritoneal dialysis, for example continual ambulatory peritoneal dialysis (CAPD) or continual cycling peritoneal dialysis (CCPD) it is the usual practice to make use of glucose as the osmotic carrier substance or osmotic active substance. However, these solutions have the disadvantage that glucose when used as the carrier substance is strongly resorbed, because of which the glucose blood level is increased, which is very disadvantageous in the presence of disturbances of carbohydrate metabolism. Dialysis solutions for peritoneal dialysis, e.g. the continuous ambulant peritoneal dialysis (CAPD) or the continuous cycling peritoneal dialysis (CCPD) are disclosed in (cf. "Praxis der CAPD", published by F. Scheler and C. Fuchs, Bibliomed, Medizinische Verlagsgesellschaft mbH Melsungen, 1981, p. 1-139).
For this reason attempts have been made over long periods of time to replace the glucose in dialysis solutions for peritoneal dialysis with other substances which do not possess the disadvantages occurring when glucose is used as the osmotic active substance, that is to say, with which there is no undesirable resorption, and with which it is also possible to have longer dwell times and, therefore, a change is only necessary after longer intervals of time. A restricted choice of replacements for glucose can be made from poly-anionic substances and glycerin. However, poly-anionic substances have the disadvantage that they can cause alteration in the size of the membrane pores, thus having a negative influence on the dialysis. Studies with poly-anionic substances have not yet progressed beyond the stage of animal experiments. Also, substantial doubts exist about the utilisation of glycerin, because glycerin has a nephrotoxic effect and, since it can be resorbed because of its low molecular weight, it can disturb the residual kidney function.
According to the DE-OS 34 28 201, an hydroxyethyl starch with a molecular weight.gtoreq.3.times.10.sup.4 Dalton and a degree of substitution in the range from 0.25 to 0.7 is proposed as the osmotic active substance in solutions for peritoneal dialysis.
However, the utilisation of such an hydroxyethyl starch, with regard to the problems of poor metabolisation of eventually absorbed hydroxyethyl starch, is unfavourable.
Hydroxyethyl starches are known from EP-A-0 402 724, which have a mean molecular weight in the range from 60,000 to 600,000, a degree of substitution MS and DS in the range from 0.15 to 0.5 and a substitution ratio C2/C6 in the range from 8 to 20. However, only the use of plasma expanders is described and no reference is made to the utilisation of hydroxyethyl starch in peritoneal dialysis.
However, from investigation, referred to in Nephron 1992, 61, 120 and in which the breakdown of hydroxyethyl starches of different molecular weights in various organs was compared, it can be gleaned that hydroxyethyl starches do not appear to be suitable for use as osmotically active substances in continuous ambulatory peritoneal dialysis.
Therefore, there still exists, as formerly, the need for dialysis solutions which contain osmotically active substances and with which the disadvantages of the known solutions do not occur.